Process of preparing sex hormones



Patented Mar. 26, 1946 2,397,426 i PROCESS or PREPARING sax HORMONESRussell Earl Marker, Mexico City, Mexico, and 1 Eugene Leroy Wittle,Detroit, Mich., assignors to Parke, Davis & Company, Detroit, Mich, a

corporation of Michigan No Drawing. Application May 24, 1944, Serial No.537,205

4 Claims.

This invention relates to a process of preparwhere R is a. member of thegroup consisting of hydrocarbon radicals and oxygenated hydrocarbonradicals, X is a halogen, and one of Y and Z is a member of the groupconsisting of hydrogen and halogen, the other being hydrogen, with anagent capable of xidatively rupturing carbon-to-carbon bonds of thegroup R, treating .the

oxidation products having a shortened sidechain thus obtained to obtainthe corresponding M-unsaturated steroids, and treating these with anagent capable of oxidizing a methylene group adjacent to a double bondthus forming the corresponding 3-keto A -unsaturated steroids having ashortened side-chain.

In greater detail, our new process consists first in forming ,a N- or A-unsaturated sterol or bile acid derivative. Because of theiravailability. we prefer to use as starting materials, the naturallyoccurring sterols in which the side-chain R.

is a hydrocarbon radical containing 8 to 10 carbon atoms. This sidechain may be saturated, as

' ing sex hormones, and more particularly, to a ride to form cholesterylchloride, and the latter reduced as for example with sodium and amylalcohol to yield A -cholestene.

The A or A-unsaturated steroidal hydrocarbpn used as a starting materialis first treated with halogen or hydrohalic acid to add the elements ofthese substances to the steroidal double bond. We prefer to usechlorine, bromine,

' hydrogen chloride or hydrogen bromide in this products are separatedso as to recover any startv step. The compound thus obtained has ahalogen atom attached to C5 and another halogen atom or hydrogen atom,depending upon whether halogen or hydrohalic acid was added, is attachedto the other carbon atom of the original double bond.

The dihalide or hydrohalide addition product thus obtained is thenoxidized under conditions sufliciently vigorous to rupturecarbon-to-carbon bonds. While a variety of agents may be employed forthis purpose, we prefer to use chromic acid, permanganic acid or theirsalts and we find it most convenient to conduct the oxidation in aceticacid below 100 C. and preferably at -60 C. r

After the oxidation has been completed, the

ing material and then the oxidation product consisting of a mixture ofsteroids having shortened, oxygenated side-chains is separated into itscomponents according to several possible methods.

It is convenient to remove the elements of haloigen or hydrohalic acidat this point by treatment with a dehalogenating or dehdrohalogenatingagent. Suitable dehalogenating agents include sodium iodide, zinc andacetic acid, me-

'A or A5), then the product formed after removal of the elements ofhalogen or hydrohalic acid, as the case may be, is a At-unsaturatedcompound. If, however, the dihalide of a A- unsaturated steroid was thesubstance oxidized,

in cholesterol CaHn or sitosterol Ciel-I21, ii?

may be unsaturated as in ergosterol CaHm. Sterols of this type arereadily converted into the corresponding 3-desoxy compounds, i. e intothe A or ii -unsaturated hydrocarbons. Thus cholesterol may be distilledat atmospheric pressure to give A -cholestene, or it may be treated withphosphorous pentachloride or thionyl chloafter removal of the elementsof halogen the product obtained is a M-unsaturated steroid and it isnecessary at some point in the process to convert-this into a A-unsaturated steroid.v This s any stage after the unreacted startingmaterial has been removed from the oxidation products but it must, ofcourse. be done before the steroid is again oxidized to form the 3-ketosteroid as set forth-later in the specification.

The mixture of oxidation products is conveniently worked up by firstseparating the acidic and the non-acidic fractions according to methodswell known in the arts. The non-acidic fraction thus obtained is furthertreated to isolate the ketonic fraction and from the ketonic fractionthe l'i keto-androstane compound and the zo-keto-pregnane compound areisolated.

The 20-keto-pregnene compound, if it still has the double bond in theM-position, may be converted into the corresponding A -pregnenone-20which may be oxidized according to our new method to formM-pregnendione-iilfl. Otherwise theA -pregnenone-20 may first beselectively reduced under conditions which leave a double bond unalteredso as to form A -pregnenol-20, the hydroxyl group of the latterprotected by conversion into a derivative hydrolyzable to regenerate A-pregnenol-20 and this derivative oxidized according to our new methodto form the corre. sponding derivative of A -pregnenol-20-one-3.

In either case the process involves the use of our new method for thepreparation of n -unsaturated 3-keto steroids from M-unsaturatedsteroids. This method consists in oxidizing to a ketone group amethylene group adjacent to a double bond and this oxidation is effectedby first protecting any hydroxyl groups by converting these intoderivatives such as acetates, benzoates, trityl ethers or-other groupshydrolyzable to give OH and oxidizing the derivative thus obtained withan agent capable of converting into a ketone group a methylene groupadjacent to a double bond. Such agents include chromic acid andpermanganic acid and their-salts, as well as selenium dioxide. Theconditions of reaction depend on the particular oxidizing agentemployed,-e. g. we prefer to use chromic acid in acetic acid at ail-60C.

The selective reduction of A -pregenonemay be accomplished with awidevariety of redueing agents. These include catalytic hydrogenation with aRaney nickel catalyst, and the combination of an alkali or alkalineearth metal or aluminum and a substance having reactive hydrogen atoms.Reducing agents of the latter 4 and Ponndorif using, for example,ammonium isopropylate and isopropyl alcohol.

Our invention may be more fully illustrated by the following examples:

Example 1 '(a) In a. 12 liter flask is Placed 230 g. of A cholestenedibromide prepared, e. g., according to Mauthner, Monatsh. 27, 421(1906), and 500 cc. of carbon tetrachloride. When solution is complete,8 liters of glacial acetic acid are added and the solution warmed to 45C. with stirring. To this stirred solution at 48-50? C. is addeddropwise a stirred solution of 320 g. of chromic anhydride in 350 cc. ofwater and 800 cc. of acetic acid over a period of four or five hours.The solution is stirred at 50 C. for six hours longer and then cooledwith cold water or ice to 30 C. Then ethyl solution over a period ofabout one-half hour to destroy any excess chromic anhydride. acetic acidis then removed under reduced pressure until the volume of the solutionhas been reduced about one-half. During the evaporation the temperatureof the solution is keptat 40-45 C. The solution is cooled slightly andthe unchanged dibromide filtered ofi! and dried. The filtrate is furtherconcentrated under reduced pressure at 40 C. until only a small quantityof acetic acid remains. This residue is diluted with 4 liters of waterand 2.5 liters of ether and stirred until all the material is insolution. The water layer is separated and extracted with 2.5 liters ofether. The combined ethereal extracts are washed well with 2 liters ofwater, 3 liters of water containing 300 cc. of cone. hydrochloric acid,and then twice with 1.5 liters of salt water, sufiicient salt beingadded to cause rapid separation of the layers. The ethereal solutionthen is evaporated to dryness, the last ether being taken ofi cautiouslyto avoid undue heat. The residue contains the dibromides of A-androstenone-l'l, A pregnenone-ZD, and A- -cholenic acid.

Instead of using A' -cholestene dibromide in the above, step, A-sitostene dichloride. or other dihalides of n -unsaturated hydrocarbonsderived from sterols may be used instead.

(b) One liter of acetic acid and 5 g. of zinc dust is added to thisresidue and the solution stirred vigorously and heated to C. on thesteam bath. A further 45 g, of zinc dust is added to this stirredsolution in small portions over a period of forty-five minutes. Then thesolution is filtered from the caked zinc and the latter washed well withacetic acid. The acetic 'acid filtrate is evaporated to dryness in vacuoon the steam bath and the residue dissolved in 2 liters of ether. Theethereal solution is washed twice with water and the acid fraction isextracted with 5% sodium hydroxide solution until all acids are removed.thereby leaving a solution containing n -androstenone-l'l and A-pregnenone-20 from which the latter product may be isolated in theknown manner. may be purified by converting the same into itssemicarbazone, hydrolyzing to the free 20-keto compound, molecularlydistilling and crystallizing from dilute alcohol.

M-pregnenone-20 may' be converted into A -pregnenone-20 by adding andthen removin the elements of hydrohalic acid as previously described.For example, a stream of dry hydrogen chloride is bubbled for severalhours through a. chloroform solution of A -pregnenone-20, cooled to 0 C.After the cold solution has stood for several hours, it is carefullyevaporated to dryness under reduced pressure leaving a residue which is5-chloropregnanone-20. This is dissolved in alcohol and refluxed for sixhours with fused potassium acetate. The resulting solution is pouredinto water fonning a precipitate of A pregnenone-20 which is collectedand dried.

E's-ample 2 The known compound A -pregnenol-3 (5) -one- 20 is treatedwith phosphorous pentachloride to obtain A -3-oh1oro-pregnenone-20 andthe latter treated to obtain A -pregnenol-20 (a) as described inapplication, Attorneys No. 32,284 which is a division of Application,Serial No. 362,836. A-pregnenol-20( may be treated to obtainapregnenone-20 in the same manner as described in Serial No. 362,836 forthe preparation of A alcohol (250 cc.) is added slowly to this stirred1s androstenone-l'l from n -androstenol-l'l.

The'

If desired, A -pregnenone-20 methanol and thus yields M-androstenone-l'lof A stream of dry hydrogen chloride is bubbled for several hoursthrough a solution of A -pregnenol-20(a) in chloroform, cooled to C.After the cold solution has stood several hours, it is carefullyevaporated to dryness-under reduced pressure on a water bath. Theresidue is chloro-pregnanol-20(m) It is dissolved in ethyl alcohol andrefluxed for six hours with 4 g. of fused potassium acetate. Theresulting solution is poured into water and the precipitate collectedand dried. This crude product is acetylated by refluxing it with aceticanhydride for two hours. Fractional crystallization of the acetylatedproduct yields A-pregnenol-20(a) acetate which may be hydrolyzedtoproduce A -pregnenol-20(a) To a solution of A -pregnenol-200x) inacetic acid is added 1.05 molar bromine in acetic acid thereby forming4,5-dibromo-pregnanol-20(a). A solution of chromic anhydride in aceticacid is added and allowed to stand at room temperature for one hourthereby forming 4,5-dibromopregnanone-20. It is then warmed with zincdust, filtered, poured into water and extracted with ether. The etherealsolution is washed well with water and dilute alkali and evaporated todryness. The residue is distilled in a molecular still under reducedpressure and then crystallized from dilute methanol to giveM-pregnenone-ZO.

Example 3 (a) d -Cholestene, prepared, 'e. g., by the reduction ofcholesteryl chloride with sodium and alcohol, is converted into5-chlorocholestane by adding hydrogen chloride as described by Mauthner,Monatsh. 28, 1113 (1907).

(b) Two hundred grams of 5-chlorocholestane in 500 cc. of carbontetrachloride and 41. of acetic acid are stirred and maintained at 50 C.whlie a solution of 150 g. of calcium permanganate in 600 cc. of water,100 cc. of sulfuric acid, and 2 l. of acetic acid is added over a periodof four hours. The mixture is stirred four hours more at 50 C., and thensulfur dioxide passed into the solution with cooling. The mixture isconcen-v trated to one-third its former volume in vacuo, 700 g. ofsodium acetate added, and the mixture refluxed for two hours. It isdiluted with water and well extracted with ether. The ethereal layer isshaken with sodium hydroxide and the sparingly soluble sodium salt whichforms is removed by filtration. Thefiltrate, consisting of an etherealand an aqueous phase, is set aside for later treatment as describedunder (d) below.

(c) The sparingly soluble sodium salt is suspended in water, and thesuspension acidified strongly. This mixture is 'well extracted withether and the latter washed and evaporated. The residue is crystallizedfrom slightly diluted acetic acid and thus yields M-cholenic acidof M.P. 160 C.

(d) The ethereal layer in the filtrate is separated and .washed wellwith sodium hydroxide solution and water. After removing the ether on asteam bath, the residue is heated with 200 cc. of acetone, some methanoladded, and the mixture chilled. The crude M-cholestene which separatesis collected and recrystallized. The combined mother liquors areevaporated to dryness, and the ketonic constituents removedin the knownmanner with Girards reagent T. The crude ketonemixture is distilledslowly in a high vacuum and a fraction collected at 70-110 C. This isiractionally crystallized from dilute The combined mother liquors fromthe above described crystallization of A -androstenone-17 containM-androstenone-l'l and A -pregnenone- 20 and, if desired, theM-pregnenone-ZO may be isolated therefrom or, alternatively, the mixedketones may be oxidized and the oxidation products separated from oneanother.

(e) The combined mother liquors are evaporated to dryness and dissolvedin 50 cc. of acetic acid. To this solution, at 45 0., there is added asolution of 1.5 g. of chromic anhydride in 20 cc. of 90% acetic acidover a period of a half hour. The mixture is poured into water,extracted with ether, and the ethereal extract washed with sodiumhydroxide solution and water. The ethereal solution is dried overmagnesium sulfate, evaporated to a, small volume, and rendered cloudy bythe addition of ligroin. On standing, crystals of A-androstenedione-3,17 separate. After recrystallization, this productmelts at 170. The mother liquor from the separation of the A -alldrostenedione-3,17 is made slightly turbid with llgroin and filteredthrough a column of alumina. The filtrate is evaporated and yields,after crystallization from dilute acetone, progesterone of M. P. 122 C.

Example 4 (a) N-cholestene is prepared by distilling cholesterol atatmospheric pressure according to the method of Heilbron and Sexton, J.Chem. Soc. 1928, 347.

(b) To 100 g. of A -cholestene in 500 cc. of carbon tetrachloride isadded'a 30% solution of bromine in carbon tetrachloride until thedoublebond is saturated with bromine. Then the mixture is warmed to 50C., 2 l. of acetic acid added, and a solution of 100 g. of chromicanhydride in 1 liter of 90% acetic acid added at 50 C. over a period offour hours. After stirring for four hours more at this temperature,150g. of zinc dust is added, in small portions, and the mixture allowedto stand overnight. The next day the solution is decanted from thesludge, and concentrated in vacuo. The residue is dissolved in water andether, the layers separated, and the ethereal layer washed with sodiumhydroxide solution. The ethereal extract contains A -androstenone-17 andA -pregnenone-20. The extract is then evaporated to dryness, and theketones removed and separated from the residue in the known manner asthe semicarbazones. The purified semicarbazone of A -pregnenone-20 ishydrolyzed to obtain A -pregnenone-20.

Example 5 (a) A -pregnenone-20 may be prepared in any of the severalways referred to in the preceding description.

(bl To a solutionof 2 g. of A -pregnenone-20 I in 30 cc. of acetic acidat 45 C. is added over a ,trated to a small volume.

Example 6 (a) A A -pregnenol-zo may be prepared in accordance with thepreceding description.

(b) To a solution of a A -pregnenol-20 in acetic acid is added at 35-450., a solution of chromic anhydride in 50 cc. of 90% acetic acid. Theaddition requires one-halt hour and the solution-is then kept at 45 C.for another half hour. The solution is poured into water and extractedwith ether. The ethereal layer is washed well with sodium carbonatesolution and water and concen- On cooling this solution for some timecrystals form and are collected. They may be recrystallized from etherto yield A*-pregnendione-3,20 identical with the known substance,progesterone.

The above examples are intended to illustrate but not to limit the scopeof our invention. Other modes of employing our process apparent to thoseskilled in the art after this disclosure, are intended to fall withinthe scope of our invention and accordingly we wish to limit the scope orour invention only as indicated in the appended claims.

What we claim as our invention is:

1. The process which comprises subjecting steroid of the formula, 7

where R is a sterol-side chain containing'ii to 10 carbon atoms and X isselected from the class consisting of chlorine and bromine, to oxidativeside chain degradation by treatment with an oxidizing agent selectedfrom the classconsisting of chromic acid, permanganic acid, and theirsalts, treating the oxidation products thus ob tained with adehalogenating agent converting v the A -unsaturated ketonic steroidsthus obtained into the corresponding zi -unsaturated steroids byaddition thereto and subsequent removal therefrom o1 hydrohalic acid,and separating A pregnenonefrom said A -unsaturated steroids.

drogen bromide, and separating from the resulting M-unsaturated ketonicsteroids, (i -pregnenone-20.

3. The process which comprisessubjecting a steroid 'of the formula,

CH; CH:

. where R is a sterol-side chain containing 8 to 10 carbon atoms and Xis selected from the class consisting of chlorine and bromine, tooxidative side chain degradation by treatment with an oxidizing agentselected from the class consisting of chromic acid, permanganic acid,and their salts, treating the oxidation products thus obtained with adehalogenating agent, separating from the A -unsaturated steroids thusobtained, A -pregnenone-20 and converting A -pregnenone- 20 into A-pregnen0ne-20 by addition thereto and subsequent removal therefrom ofhydrohalic acid.

4. A -pregnenone-20.

RUSSELL EARL MARKER. EUGENE LEROY W'II'I'LE.

